It has taken us a while, but we are now getting track down in the fiddle yard. Here is the evidence.
We are using PVA glue to hold it down.
We have two metal ‘U’ tubes to keep it straight, one 8 mm to go between the rails to ensure that one track is straight, and one 10 mm to go between tracks to ensure they are parallel. We started from the central track of the fiddle yard, and are working outwards from there.